Bitumen extraction and asphaltene removal from heavy crude using high shear

Abstract

Herein disclosed is a method of removing at least one component from a feed by subjecting the feed to high shear in the presence of carbon dioxide to produce a high shear-treated product and separating the at least one component from the high shear-treated product to produce a component-reduced product. Also disclosed is a method of removing asphaltenes from asphaltenic oil by subjecting the asphaltenic oil to a shear rate of at least 10,000 s−1 in the presence of carbon dioxide to produce a high shear-treated product and separating asphaltenes from the high shear-treated product to produce an asphaltene-reduced product oil. Systems are also provided for carrying out the methods.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61 / 262,027, filed Nov. 17, 2009, the disclosure of which is hereby incorporated herein by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]Not Applicable.BACKGROUND[0003]1. Technical Field[0004]The present invention relates to systems and methods for enhanced recovery and processing of heavy crude and / or bitumen. More particularly, the present invention relates to the high shear removal of asphaltenes from feeds comprising bitumen and / or heavy crude oil and the high shear separation of water and mineral solids from tailings conventionally sent to a tailings pond.[0005]2. Background of the Invention[0006]Large deposits of heavy hydrocarbon sometimes referred to as bitumen are located in many countries around the world. Bitumen may be recoverable by means of secondary or tertiary recovery processes that involv...

AI Technical Summary

Benefits of technology

[0023]In embodiments, at least a portion of the tailings are produced by introducing a bitumen froth from a separation cell of a bitumen extraction process into one or more centrifuge and extracting the at least a portion of the tailings from the one or more centrifuge. In embodiments, subjecting the feed comprising tailings to high shear in the presence of carbon dioxide reduces the pH to less than about 6. In embodiments, subjecting the feed to high shear converts the caustic in the tailings to sodium bicarbonate, enhancing the rate of separation of water from the tailings relative to conventional tailings treatment processes.

[0030]According to embodiments of this disclosure, a high shear device is used to improve the recovery and processing of heavy crude bitumen. In one aspect of the present invention a high shear device is used in combination with reactive gas (e.g. carbon dioxide) to enhance the separation of clay and other inorganic mineral solids from the bitumen once it is extracted from the ground. In another aspect of the present invention a high shear device is used in combination with carbon dioxide to enhance the separation of asphaltenes and other undesirable elements of bitumen following removal of inorganic contaminants, thus allowing for easier transportation and downstream processing of the recovered bitumen.

[0031]Certain embodiments of the above-described methods or systems potentially provide overall cost reduction by reducing the size and / or number of downstream purification apparatus / steps, providing oil having reduced levels of impurities including, but not limited to, asphaltenes, sand, silt, solids, sulfur and / or other heavy metals, and / or water, permitting operation at low temperature and / or pressure relative to conventional heavy crude oil or bitumen processing, and / or reducing capital and / or operating costs of bitumen extraction or heavy crude oil processing. These and other embodiments and potential advantages will be apparent in the following detailed description and drawings.

Problems solved by technology

Many of these heavy hydrocarbon deposits contain high concentrations of asphaltenes that contribute to difficulties in recovery, transporting and upgrading.

Heavy crude oil or crude bitumen extracted from the earth is in a viscous, solid or semi-solid form that does not flow easily at normal oil pipeline temperatures, making it difficult to transport and expensive to process into gasoline, diesel fuel, and other products.

The economic recovery and utilization of heavy hydrocarbons, including bitumen, is a significant energy challenge.

The demand for heavy crudes, such as those extracted from oil sands, has increased significantly due to dwindling reserves of conventional lighter crude.

Due to the formation of stable emulsions containing fine tar-sands ore particles, water and bitumen oils, water-based processes are not particularly efficient, especially on ore of lower bitumen content.

The treatment of emulsions comprising large volumes of water, bitumen oils and fine tar-sands ore particles has proven challenging.

Percolation and immersion-type extractors have been used, but the need for special designs and scale-up for processing of abrasive tar-sands make economical extraction difficult.

For example, the solvent to bitumen ratio needed for efficient extraction is generally high, up to 10:1, producing concomitantly high capital and utilities costs for recovery of the solvent via, for example, distillation.

Stripping of residual solvent is a capital and energy intensive undertaking.

Existing solvent extraction methods for dissolving bitumen oils from tar-sands, for example, as disclosed in U.S. Pat. No. 4,160,718 issued to Rendall, typically involve environmentally unacceptable losses of solvent and additional problems associated with the hazards posed by the necessary storage of large solvent inventories and the need for large quantities of water.

These methods all have commercial and / or ecological drawbacks, rendering them undesirable.

A serious problem, however, in using a solvent extraction process to remove bitumen from such a carbonaceous solid is that fines, primarily particles less than 50 microns in diameter, are carried over in the solvent-dissolved bitumen extract.

Failure to remove the fines results in an undesirable high-ash bitumen product as well as problems with plugging of equipment used in the separation process, especially, for example, filtration equipment.

Similar problems arise when other carbonaceous liquids besides bitumen, such as coal liquid or shale oil, are used.

The naphtha must be distilled and recycled, adding to energy costs.

Changes in temperature and / or composition may cause the asphaltenes to fall out of solution, necessitating pipeline cleaning.

At lower solvent levels, commonly used in solvent deasphalting, substantial non-asphaltenic material precipitates with the asphaltenes, resulting in undesirable oil losses.

Furthermore, solvent deasphalting relies on multiple theoretical stages of separation of barely immiscible hydrocarbon liquids, such stages are intolerant to the presence of water.

The oil yield of solvent deasphalting is also limited by the high viscosity of the resultant asphaltic materials, particularly for high viscosity bitumen feeds.

It is thus difficult to obtain high quality oil with high oil yield due to the difficulties in achieving clean separation of the oil and asphaltic fractions.

This viscous liquid must be heated to a high temperature in order to be transportable, causing fouling and plugging limitations.

However, only about 50% of the asphaltenes may be readily removed with this treatment even with multiple stages and complete removal of asphaltenes is thus not practical.

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