US20070125686A1

US20070125686A1 - Method for processing oil sand bitumen

Info

Publication number: US20070125686A1
Application number: US11/524,065
Authority: US
Inventors: Changbo Zheng; Yuzhen Zhang; Zhongwen He; Qiang Liu; Huize Huang
Original assignee: Individual
Current assignee: China National Offshore Oil Corp CNOOC
Priority date: 2005-12-07
Filing date: 2006-09-19
Publication date: 2007-06-07
Also published as: CN1325605C; CN1775909A; WO2007065327A1; CA2570231A1

Abstract

This invention relates to a method for processing oil sand bitumen including solvent deasphalting and visbreaking oil sand bitumen to yield de-oiled asphalt (DOA) and components capable of being transmitted in pipeline. The method for processing oil sand bitumen provided by this invention can effectively transmit oil sand bitumen in pipeline with the advantages of simple operation low equipment cost and significantly reduced operating cost. This method not only can solve the problems arising from enormous working capital required for purchasing diluting agent needed by the traditional unit for processing oil sand bitumen and complications in looking for users, but also can drastically reduce the high investment and high processing cost of such main upgrading avenues as coking and converting heavy oils to light distillates. This invention can enhance the effective products yield and increase the sales income. This method for processing oil sand bitumen can make the recovery of sulfur contained therein by means of the downstream processes easier to significantly reduce the sulfur recovery cost and ensure compliance with the pollutants emission standard.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present patent application claims priority from Chinese Patent Application No. 200510127799.1, filed on Dec. 7, 2005.

FIELD OF THE INVENTION

This invention relates to a method for processing oil sand bitumen, in particular to a method for processing oil sand bitumen to enhance the pipeline transmission performance thereof.

BACKGROUND OF THE INVENTION

Oil sand bitumen is actually a highly viscous asphalt, characterized in a high density (0.97-1.015 g/cm³at normal temperature and under normal pressure), a high viscosity (generally 100000-1000000 cSt at room temperature), and high contents of sulfur, asphaltenes and nickel and vanadium. The oil sand bitumen averagely comprises 83.2% carbon element and 10.4% hydrogen element with a very high C/H ratio and a high viscosity and almost cannot flow at ambient temperature.
Currently the oil sand bitumen is mined mainly by the following three processes:
1. Cyclic Steam Stimulation. In this process, a high-pressure steam is injected into the oil sand layer and remains there for several weeks. The heat can soften the bitumen, while the steam can dilute the bitumen and separate it from the sand, and then the bitumen capable of flowing is pumped onto the ground.
2. Steam Assisted Gravity Drainage. In this process, two parallel wells are drilled in the oil sand layer with one well located upper and the other located lower, and steam is continuously injected into the upper well. When oil sand layer is heated by the steam, the oil sand is softened and flows to the lower well by gravity and then can be pumped onto the ground.
3. Open Pit mining. In this process, the bitumen-containing oil sand is excavated by machine and then is flushed with solvent and caustic water, and the mixtures of oil and bitumen strip from the sand particles or the mixtures of caustic water and bitumen are evaporated to remove the solvent or water to yield oil sand bitumen.
The oil sand bitumen obtained by the above-mentioned three processes can be upgraded via hydrogenation or decarbonization followed by conventional crude oil processing to yield oil and petrochemical products. The main refining processes adopted hereof comprise the atmospheric distillation, vacuum distillation, and the delayed coking followed by hydrofining or hydrotreating to route the products to the blending unit in order to manufacture the Synthetic Crude Oil (SCO), which can be processed at oil refining enterprises to yield commodity oil products such as fuel oil, lubricating oil, asphalt and petrochemicals needed by the market.
Since the oil sand bitumen almost cannot flow at normal temperature because of its extremely high viscosity, it is necessary to upgrade the oil sand bitumen at the mining site to reduce its viscosity or improve its quality to meet the requirements for pipeline transmission so that the oil sand bitumen can be available on the market to play its role. Currently, the method for processing the oil sand bitumen mainly comprises the method of mixing the bitumen with a diluting agent to reduce the viscosity of oil sand bitumen. This method is performed by mixing the oil sand bitumen with a diluting agent at the oilfield and transmitting this mixture in pipeline, at the terminal of which the oil sand bitumen in admixture with the diluting agent is either handed over to the end user, or the diluting agent is reclaimed and reused after delivering the oil sand bitumen to the end user with the oilfield paying the “carrier rent and carrier loss fees”. Since it is economically unreasonable to sell the diluting agent at a price lower than its original cost, the Oil Sand Bitumen Company generally uses the diluting agent provided by the Pipeline Company as the carrier. The diluting agents adopted by this process generally comprise light naphtha, condensate or synthetic crude oil (SCO), which is the product obtained by processing the oil sand bitumen by the delayed coking process. The amount of the diluting agent used is approximately 66% (by volume) of the oil sand bitumen. Use of a significant amount of high-value diluting agent would require enormous working capital and is economically unreasonable. Furthermore, in this process, the oil sand bitumen purchaser or the Oil Sand Bitumen Company itself is required to set up a distillation unit at the pipeline terminal and separate the diluting agent for recycling. However, it is difficult to effectively develop the oil sand bitumen market because of impediments for finding the right users that can meet the above-mentioned conditions. Additionally, transmit of the oil sand bitumen in admixture with the diluting agent would in itself increase the pipeline transmit load.
In addition, some oil sand bitumen companies apply the upgrading process consisting of delayed coking as the main means to “convert heavy oils into light ones” upon processing the oil sand bitumen. The high-sulfur petroleum coke, a by-product obtained by said processing process, is sold at a much lower price and the distribution thereof is difficult owing to lack of buyers. It is well known that adoption of the technology for hydroprocessing the tower bottom heavy oil to reduce the sulfur content in petroleum coke needs high operating cost and is not beneficial for the investors.
CN 1233644A discloses a “mild thermal cracking-solvent deasphalting” combination process, which comprises feeding the straight-run heavy components into a thermal cracking reactor and mild thermal cracking them with a temperature of 380-450° C., a pressure of 0-0.5 MPa and a residence time of 10-120 minutes; feeding the resulted streams after cracking reactions into a light ends separation unit to separate light ends and heavy components which is used as feed oil for the solvent deasphalting unit; feeding a mixture of a solvent which is one or more of selected from the group consisting of propane, isobutene, normal butane, and normal pentane and a feed oil for the solvent deasphalting unit at a volume ratio of 3-12:1 through a static mixer into a solvent deasphalting unit followed by two-stage or one-stage solvent deasphalting under the precritical or supercritical conditions of the solvent, with the solvent being reclaimed for recycling. This process is aimed at increasing the light distillate yield and improving the quality of the same.
CN 1485412A discloses a “solvent deasphalting-mild thermal cracking” combination process, which comprises the following steps: separating the feedstock in a distillation unit to separate heavy components, feeding the heavy components thus obtained into the upper part of an extraction tower of the solvent deasphalting unit while routing the solvent into the lower part of the extraction tower at a predetermined ratio, thereby the heavy components and solvent enter into the extraction tower in countercurrent contact extraction with each other; sending the deasphalted oil (DAO) containing a large amount of solvent back for solvent recovery, while discharging the DOA containing a small amount of solvent from the bottom of extraction tower and then feeding the same into a visbreaking unit, where the DOA goes visbreaking reactions in a visbreaking reactor; and feeding the streams exiting from the visbreaker into a flash distillation tower to separate the visbreaker gas, visbreaker gasoline and visbreaker residuum. The main purpose of this method is to enhance the linear velocity of material streams in furnace tubes and extend the operating cycle to find an outlet for the gilsonite (hard bitumen) by reducing the energy assumption for solvent recovery and alleviating the coking of DOA inside the furnace tubes.
Although the above-mentioned prior arts has disclosed the methods for processing the heavy residuum through the combination method comprising mild thermal cracking and solvent deasphalting, the feedstocks adopted are heavy residuum and their purposes are to increase the light distillate yield and improve the product quality. As far as the present inventors know, it has not been disclosed that a method for processing oil sand bitumen via a combination method of mild thermal cracking and solvent deasphalting to improve its pipeline transmission performance and increase the economic benefits of the oilfield.

SUMMARY OF THE INVENTION

An object of the present invention is to overcome the above disadvantages existing in the prior arts, i.e. high costs in pipeline transmission and processing of the oil sand bitumen, and to provide a low-cost method for processing and pipeline transmitting oil sand bitumen.
Another object of the present invention is to provide on the above-mentioned basis a method for processing the oil sand bitumen with better overall economic benefits.
The present invention provides a method for processing oil sand bitumen, which comprises the steps of visbreaking and solvent deasphalting the oil sand bitumen to yield DOA and components capable of being transmitted in pipeline.
The method for processing oil sand bitumen provided by this invention may further comprise a bitumen gasification step for gasifying obtained DOA upon contact with oxygen to generate steam and syngas. The syngas obtained from the bitumen gasification can be further used as the fuel for a steam-electricity cogeneration unit to generate steam and electricity necessary for the production operation at oilfield.
The method for processing oil sand bitumen provided by this invention can by means of visbreaking and solvent deasphalting reduce the viscosity of bitumen products and effectively solve the problem concerning the pipeline transmission of the oil sand bitumen. The method provided by this invention is simple in operation, low in equipment cost and drastically low in operating cost, and not only can solve the problem concerning high investment required by purchasing massive diluting agent for the traditional oil sand bitumen processing unit, but also can remarkably reduce the high investment and processing cost required by the upgrading means mainly composed of the coking and hydrogenation processes. On the other hand, this invention can also by means of steam-electricity cogeneration technology convert the DOA mainly comprising heavy asphaltenes and resins into heat energy and electricity to provide a significant amount of steam and power to save massive natural gas necessary for steam generation at the oilfield, which is especially of great significance for the oilfield adopting the steam-aided gravitational drive (SAGD) technology. In the meantime, it is possible to reclaim a large amount of sulfur in the sulfur recovery unit (SRU), which is advantageous in solving the emission problem in compliance with environmental regulations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram showing one embodiment of processing oil sand bitumen provided by this invention;
FIG. 2 is a flow diagram showing another embodiment of processing oil sand bitumen provided by this invention; and
FIG. 3 is a flow diagram showing the process of DOA gasification provided by this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The method for processing oil sand bitumen provided by this invention comprises the steps of visbreaking and solvent deasphalting the oil sand bitumen to yield DOA and components capable of being transmitted in pipeline.
The oil sand bitumen described in this invention generally refers to the oil sand bitumen obtained through open pit mining or exploited through drilling coupled with steam heating followed by preliminary removing minerals such as sand and clay contained therein.
The components capable of being transmitted in pipeline described in this invention refer to the materials that can be transmitted in pipeline at conventional transmission conditions in the crude oil transportation field. Preferably, said components capable of being transmitted in pipeline refer to the components having a viscosity less than 350 cSt at 8° C.
The term “visbreaking” mentioned in this invention refers to a mild thermal cracking process and is mainly used to reduce the viscosity of the material stream to the maximum degree to improve the pipeline transmission performance of the oil sand bitumen. The viscosity reduction is achieved mainly through thermal cracking non-asphaltenes. Visbreaking is a matured oil refining process aimed at producing light distillates from heavy oil, and its process conditions are well known to the person skilled in the art. The process conditions of visbreaking used herein is not specially limited and said visbreaking can be carried out at different reasonable temperature and pressure conditions. It is appreciated that the person skilled in the art can easily find out suitable conditions to achieve the objectives of this invention in accordance with the technical solution of this invention. The visbreaking reactions described in the embodiments of this invention should be preferably carried out under the conditions of a temperature range of 350-500° C., a pressure range of 0.3-15 MPa and a residence time of 1-6 hours, and more preferably under the conditions of a temperature of 400-430° C., a pressure of 2-10 MPa and a residence time of 2-4 hours.
The solvent deasphalting mentioned in this invention refers to a process of separating the components contained in the oil sand bitumen according to the rule of similarity between organic solvents and the components contained in oil sand bitumen and is a liquid-liquid extraction process, which can be carried out in various vessels, preferably in the extraction tower of solvent deasphalting unit in order to facilitate the large scale commercial production. After being processed in solvent deasphalting unit, the oil sand bitumen materials thus obtained are separated into two parts, one of which dissolves in the solvent and the other does not dissolve. Since the materials dissolved in the solvent are generally components with low molecular weight, they flow out from the tower overhead together with the solvent, known as the DAO, whereas the insoluble in the solvent are heavy components known as the DOA, and generally flow out from the deasphalting tower bottom. The DOA generally comprises heavy asphaltenes and resins.
The solvent used in the solvent deasphalting step in this invention is not especially limited and may be various organic solvents including the low-molecular hydrocarbon solvent such as one or more selected from the group consisting of propane, n-butane, isobutene, n-pentane, isopentane, n-hexane, cyclohexane, heptane and petroleum ether, preferably one or more of the hydrocarbons having 3-5 carbon atoms, namely propane, n-butane, isobutene, n-pentane and isopentane. Preferably, the solvent is used in an amount of 3-12 and more preferably 4-10 (by volume) times of that of the feedstock. Said solvent deasphalting may be supercritical solvent deasphalting, precritical solvent deasphalting or conventional solvent deasphalting, and preferably the supercritical solvent deasphalting process, which is carried out under supercritical conditions. Said supercritical conditions comprise an operating temperature higher than the critical temperature of the solvent and an operating pressure higher than the critical pressure of the solvent, and the critical values of temperature and pressure may vary depending on the solvent. Within the range of the above-mentioned preferable solvents, the extraction temperature for supercritical solvent deasphalting is 10-200° C., and the pressure is 0.2-10 MPa, and more preferably the extraction temperature is 140-180° C. and the pressure is 3-8 MPa.
In this invention, the oil sand bitumen may be subjected to solvent deasphalting followed by visbreaking, or may be subjected to the visbreaking followed by solvent deasphalting. Different operating sequences can have a slight influence on the operating conditions of each step, but both of them are realizable within the conditions provided by this invention.
According to one embodiment of this invention, the method for processing the oil sand bitumen includes visbreaking the oil sand bitumen and routing the products thus obtained as the feedstock to the solvent deasphalting unit to yield DOA and DAO. Whether the solvent comprised therein is reclaimed or not, said DAO is used as the components capable of being transmitted in pipeline. In order to reduce the load of visbreaker, said oil sand bitumen is preferably routed into a distillation unit to separate the components capable of being transmitted in pipeline, and then the heavy components obtained in the distillation unit is subjected to deasphalting. Said distillation may be atmospheric distillation and/or vacuum distillation. The conditions of said distillation can be selected by the ordinary person skilled in the art according to the target fraction that needs to be separated. The heavy components mentioned herein are preferably the components boiling at 180° C. or more. Similarly, in order to reduce the load of solvent deasphalting unit, the products obtained by visbreaking is preferably routed into a light ends separation unit to separate the components capable of being transmitted in pipeline, and then the heavy components obtained in the light ends separation unit is subjected to solvent deasphalting. Said light ends separation unit may be various light ends separation units, for instance, an atmospheric distillation tower, a vacuum distillation tower or a flash distillation tower. The operation conditions of said light ends separation can be selected by the ordinary person skilled in the art according to the target fractions that need to be separated. The heavy components mentioned herein are preferably the components boiling at 180° C. or more, and more preferably the components boiling at 500° C. or more.
The above-mentioned embodiment can be realized through the process flow sheet shown in FIG. 1 (visbreaking-solvent deasphalting): the oil sand bitumen is routed into a distillation unit, in which the oil sand bitumen is separated into low-boiling components as the components capable of being transmitted in pipeline and heavy components, and then the high-boiling distillation residuum is routed into a visbreaking unit to be visbroken under the corresponding conditions with the visbreaking products being routed into the light ends separation unit to be separated into low-boiling components as the components capable of being transmitted in pipeline and high-boiling heavy components used as the feedstock for solvent deasphalting through contact extraction by means of the hydrocarbon solvent in the solvent deasphalting unit. After solvent deasphalting, the DAO containing a significant amount of solvent and the DOA with a small amount of solvent or without solvent are obtained, and the DAO is separated from the tower overhead to be used as the components for pipeline transmission, whether the solvent contained therein is reclaimed or not. The reclaimy of solvent from said DAO can be achieved by means of the known methods, such as by means of distillation or gas-solid separation. Said DOA is discharged from the tower bottom.
In accordance with another embodiment of this invention, the method for processing oil sand bitumen provided by this invention includes the deasphalting of bitumen from oil sands to yield the DOA and the DAO and routing said DAO, whether the solvent contained therein is reclaimed or not, as the feedstock to the visbreaker to obtain the components capable of being transmitted in pipeline. In order to reduce the solvent deasphalting load to further save the cost, preferably the method provided by the present invention comprises separating the components capable of being transmitted in pipeline from the oil sand bitumen in the distillation unit and then solvent deasphalting the heavy components obtained from the distillation unit. Said heavy component mentioned herein preferably refers to a fraction boiling above at least 180° C., and more preferably a fraction boiling above 500° C. Said distillation unit may include the atmospheric distillation unit and the vacuum distillation unit. In this embodiment, said oil sand bitumen is firstly separated in the atmospheric distillation unit into the overhead components capable of being transmitted in pipeline and the tower bottom atmospheric residuum (AR), and then the AR is routed into a vacuum distillation unit to be separated into vaccuum tower overhead oil and vacuum residuum, which is solvent deasphalted to yield the DOA and the DAO. Said DAO, whether the solvent contained therein is reclaimed or not, is commingled with the vacuum tower overhead oil to serve as the feedstock for visbreaking. Said DOA is discharged from the tower bottom.
The above-mentioned embodiment can be realized through the process flow sheet shown in FIG. 2 (solvent deasphalting-visbreaking): The oil sand bitumen is fed into the atmospheric distillation section of the distillation unit, in which the low-boiling components contained in the oil sand bitumen are directly separated out as the components capable of being transmitted in pipeline, and the tower bottom AR is fed into the vacuum distillation section of the distillation unit to be separated into the vacuum tower overhead oil and vacuum residuum. Said vacuum residuum is in contact with a hydrocarbon solvent to be subjected to contact extraction in solvent deasphalting unit. After solvent deasphalting, the DAO containing a significant amount of solvent and the DOA with a small amount of solvent or without solvent are obtained. And the DAO is separated from the tower overhead and whether the solvent contained therein is reclaimed or not, the DAO is commingled with said vacuum tower overhead oil, and fed into the visbreaking unit to be subjected to visbreaking under the conditions of visbreaking. The products of visbreaking are used as the components capable of bing transmitted in pipeline. The recovery of solvent from said DAO can be achieved by means of the known methods, such as by means of distillation or gas-solid separation. Said DOA is discharged from the tower bottom.
As shown in FIG. 1 and FIG. 2, the above-mentioned method for processing the oil sand bitumen may also include separating the gaseous components from those components capable of being transmitted in pipeline and delivering them to the oilfield fuel system to be used as fuel or to be marketed.
In the prior art, the DOA obtained by solvent deasphalting is directly used as the starting material for making the road asphalt. The present inventor has discovered that gasification of the DOA upon contact with an oxidative gas can produce a large amount of heat for steam generation, which is exactly needed by the petroleum exploitation industry, and can also produce a significant amount of syngas, such as carbon monoxide and hydrogen and the like. The syngas thus obtained can be used as the fuel for a steam- electricity cogeneration unit to generate the steam and electricity much needed by the oilfield production activities. Therefore, the method for processing the oil sand bitumen provided by this invention also preferably includes the step for gasification of the DOA. The process flow sheet of said gasification step is shown in FIG. 3, wherein the DOA feedstock is in contact with an oxidative gas in the bitumen gasification unit to undergo non-complete oxidation reactions at a temperature of 200-1500° C. and a pressure of 2.0-10.0 MPa to yield the syngas. Said oxidative gas may be oxygen or air. Since the syngas produced by this method comprises significant amount of sulfur and metal elements derived from the oil sand bitumen, the method provided by this invention also preferably includes the step for recovery of sulfur. Said sulfur recovery step is carried out in the sulfur recovery unit (SRU). The syngas after reclamation of sulfur and metals contained therein becomes a purified gas and can be directly used as the feedstock of the cogeneration unit. As a result, no only a sizable amount of sulfur can be produced as a by-product, but also the environmental pollution caused by combustion of sulfur comprised in the syngas can be alleviated. The sulfur reclaimed thereby can be processed into solid sulfur, liquid sulfur, sulfuric acid and other sulfur products. Accordingly, said method for processing oil sand bitumen provided by this invention also preferably comprises the steam-electricity cogeneration step, and the fuel of which is the syngas formed during bitumen gasification. Said steam-electricity cogeneration unit is a unit that can generate steam and electricity at the same time and also represents a matured technique, which usually uses the syngas as the fuel with the ratio of steam and electricity generated being adjustable depending on the demand. For example, said steam-electricity cogeneration unit includes but is not limited to the corresponding facilities and equipment made by the GE Company. Said sulfur recovery can be, for instance, realized through scrubbing syngas followed by using relevant technical for sulfur recovery.
On one hand, the method for processing the oil sand bitumen provided by the present invention can solve the problem concerning the pipeline transmission of oil sand bitumen by reducing the viscosity of bitumen products via solvent deasphalting and visbreaking and separating and pipeline transmitting the light components from oil sand bitumen as the components capable of being transmitted in pipeline. On the other hand, the method for processing oil sand bitumen provided by this invention can also bring about optimal overall economic benefits, which are especially important for the oilfield using the SAGD technology, via gasification and purification the DOA that is rich in heavy asphaltenes and resins by gasification step and routing the resulted purified syngas to a steam-electricity regeneration unit as the fuel and converting the DOA into heat and electrical energy on the spot to provide a significant amount of steam and electricity to meet the oilfield production needs, which can save an enormous amount of natural gas which would be purchased for steam generation along with savings in expenses for the DOA transportation, Meanwhile, a large amount of sulfur can be reclaimed after cleanup operation in the SRU, which is advantageous in solving the emission problems. By the above-mentioned processing method, all components contained in the oil sand bitumen feedstock can play their roles to the maximum extent and thus significantly improve the utilization and economic benefits of the oil sand bitumen. Furthermore, the process provided by this invention is advantageous of simple operation, low equipment cost and greatly reduced operating cost, which not only can solve the problem associated with large investment in purchase of the diluting agent needed by the traditional unit for processing the oil sand bitumen, but also can reduce the high investment cost and high processing cost of the upgrading method based on the main avenues of coking and hydrogenation processes.
The present invention will be detailed illustrated by the following examples, which is just for purpose of illustration but not any limit to the present invention. The oil sand bitumen used in the following examples is the oil sand bitumen excavated in a preheated state produced at a company with its major properties presented in the following Table 1, while butane and pentane are obtained from the commercial units. The extraction tower for solvent deasphalting is a medium-size solvent deasphalting unit with a capacity of 10 kg/h, and the capacity of the visbreaker is 10 kg/h, and bitumen gasification unit is a gasification unit licensed by GE, whereas SRU is used to reclaim the sulfur.

EXAMPLE 1

According to the process shown in FIG. 1, the oil sand bitumen is routed to the distillation unit to directly separate the components boiling below 200° C. as the components capable of being transmitted in pipeline from the oil sand bitumen, with the remaining high-boiling point distillation residue entering the visbreaking unit to be subjected to visbreaking at a temperature of 400° C., a pressure of 0.5 MPa and a residence time of 2 hours. The visbreaking products are routed to the light ends separation unit, where the visbreaking products are separated into the components boiling below 500° C. as the components capable of being transmitted in pipeline and the remaining high-boiling point heavy components used as the feedstock of the solvent deasphalting. Said heavy components is carried out the contact extraction with n-butane solvent in the solvent deasphalting unit under the following conditions: a tower bottom temperature of 140° C., a tower overhead temperature of 160° C., a pressure of 6 MPa, and a ratio between n-butane and the feedstock i.e. high boiling point heavy components of 4:1. After solvent deasphalting, the DAO containing a significant amount of solvent and the DOA with or without a slight amount of solvent are obtained. The DAO is separated from the tower overhead and can be used as the components capable of being transmitted in pipeline after reclamation of the solvent. The components capable of being transmitted in pipeline obtained in all the above-mentioned processing steps are gathered and combined, from which samples are taken for analysis to determine the viscosity, density and boiling point thereof. The results are presented in the following Table 1. Said DOA is discharged from the tower bottom and used as the feedstock to the cogeneration unit of steam and electricity after being subjected to gasification and sulfur removal.

EXAMPLE 2

According to the process shown in FIG. 2, the oil sand bitumen is routed to the atmospheric distillation unit to directly separates the tower overhead components boiling below 200° C. as the components capable of being transmitted in pipeline from the oil sand bitumen, with the AR from the tower bottom being routed to the vacuum distillation unit and being separated into the tower overhead oil boiling between 200-500° C. and the vacuum residuum (VR) boiling above 500° C. Said VR is subjected to contact extraction with the pentane mixed solvent in the solvent extraction unit under the following conditions: a tower bottom temperature of 150° C., a tower overhead temperature of 170° C., a pressure of 5 MPa, and a solvent ratio of 4:1. After the step of solvent deasphalting, a DAO comprising a large amount of solvent and a DOA comprising little or a little of solvent are obtained. The DAO is separated from the tower overhead and is combined after solvent recovery with said vacuum tower overhead oil and then both are routed into the visbreaking unit to visbreaking under the following conditions: a temperature of 430° C., a pressure of 2 MPa, and a residence time of 3 hours. The visbreaker products are used as the components capable of being transmitted in pipeline. The components capable of being transmitted in pipeline obtained in all the above-mentioned processing steps are gathered and combined, from which samples are taken for analysis to determine the viscosity, density and boiling point thereof. The results are shown in the following Table 1. Said DOA is discharged from the tower bottom and used as the feedstock to the cogeneration unit of steam and electricity after gasification sulfur removal.

	TABLE 1


	Product
	Components capable of being

Feedstock

transmitted in pipeline

		Viscosity			Viscosity
example	Density	(cSt)	Density	Distillation	(cSt)
number	(g/cm³)	(at 25° C.)	(g/cm³)	range (° C.)	(at 8° C.)

Example 1	1.018	400000	0.98	≦650	300
Example 2	1.018	421400	0.99	≦650	310

It can be seen from the above Table 1 that, via the solvent deasphalting and visbreaking steps, the method for processing the oil sand bitumen provided by the present invention can significantly reduce the viscosity of the bitumen products and make the non-asphaltene fraction separated from the oil sand bitumen as the components capable of being transmitted in pipeline and thus effectively solves the problem concerning pipeline transmission of the oil sand bitumen.

Claims

1. A method for processing oil sand bitumen, characterized in comprising steps of solvent deasphalting and visbreaking oil sand bitumen to yield de-oiled asphalt and components capable of being transmitted in pipeline.

2. A method for processing oil sand bitumen as claimed in claim 1, wherein the method comprises visbreaking oil sand bitumen and solvent deasphalting the products obtained by visbreaking to yield de-oiled asphalt and de-asphalted oil, and the de-asphalted oil, whether the solvent contained therein is reclaimed or not, is used as the components capable of being transmitted in pipeline.

3. A method for processing oil sand bitumen as claimed in claim 2, wherein prior to visbreaking, the oil sand bitumen is separated in a distillation unit into components capable of being transmitted in pipeline and heavy components, and then the heavy components thus obtained are subjected to visbreaking.

4. A method for processing oil sand bitumen as claimed in claim 3, wherein said heavy components are components boiling at 180° C. or more.

5. A method for processing oil sand bitumen as claimed in claim 2, wherein prior to solvent deasphalting, the products obtained by visbreaking are separated in a light ends separation unit into components capable of being transmitted in pipeline and heavy components, and then the heavy components thus obtained is subjected to solvent deasphalting.

6. A method for processing oil sand bitumen as claimed in claim 5, wherein said heavy components are components boiling at 180° C. or more.

7. A method for processing oil sand bitumen as claimed in claim 1, wherein the method includes solvent deasphalting oil sand bitumen to yield de-oiled asphalt and de-asphalted oil and routing the de-asphalted oil, whether the solvent contained therein is reclaimed or not, as the feedstock to visbreaking to obtain the components capable of being transmitted in pipeline.

8. A method for processing oil sand bitumen as claimed in claim 7, wherein prior to solvent deasphalting, the oil sand bitumen is separated in a distillation unit into the components capable of being transmitted in pipeline and heavy components, and then the heavy components thus obtained are subjected to solvent deasphalting.

9. A method for processing oil sand bitumen as claimed in claim 8, wherein said heavy components are compents boiling at 180° C. or more.

10. A method for processing oil sand bitumen as claimed in claim 8, wherein said distillation unit includes an atmospheric distillation unit and a vacuum distillation unit, and the oil sand bitumen is firstly separated into the components capable of being transmitted in pipeline and the tower bottom atmospheric residuum in the atmospheric distillation unit, and then the tower bottom atmospheric residuum is separated into vacuum tower overhead oil and vacuum residuum in the vacuum distillation unit; said VR is subjected to solvent deasphalting to yield de-oiled asphalt and de-asphalt oiled, and said de-asphalt oiled, whether the solvent contained therein is reclaimed or not, is commingled with the vacuum tower overhead oil to serve as the feedstock for visbreaking.

11. A method for processing oil sand bitumen as claimed in claim 1, wherein said solvent deasphalting is carried out under the conditions of solvents being hydrocarbons having 3-5 carbon atoms, the volume ratio of the solvent to the feedstock being 3-12:1 (v/v), the temperature being 10-200° C., and the pressure being 0.2-10 MPa.

12. A method for processing oil sand bitumen as claimed in claim 1, wherein said visbreaking is carried out under the conditions of the temperature being 350-500° C., the pressure being 0.3-15 MPa, and the residence time being 1-6 hours.

13. A method for processing oil sand bitumen as claimed in claim 1, wherein the gaseous hydrocarbons generated can be separated to be used as fuel or be marketed.

14. A method for processing oil sand bitumen as claimed in claim 1, wherein the method further comprises a bitumen gasification step for gasifying said de-oiled asphalt upon contact with oxygen to generate steam and syngas.

15. A method for processing oil sand bitumen as claimed in claim 14, wherein said bitumen gasification step is carried out under the conditions of a temperature being 50-1500° C. and a pressure being 2.0-10.0 MPa.

16. A method for processing oil sand bitumen as claimed in claim 14, wherein the method further comprises a steam-electricity cogeneration step, of which the fuel used is the syngas generated by the bitumen gasification.