In most in situ oil sands operations, natural gas is used to generate steam to extract the thick, sticky bitumen before it is blended with diluent so it can be piped to refineries in the U.S. for processing.
Using technology that has been applied commercially in the wood industry and that is similar to technologies used in most refineries, Ivanhoe Energy is commercializing a process that partially upgrades the heavy oil in the field.
HTL Feedstock Test Facility in San Antonio, Texas
HTL (heavy to light oil) is a proprietary technology that converts bitumen to a higher-value, lighter product that can be transported by pipeline. Not only does it create a more valuable product and avoid the need for diluent, it also converts byproducts to energy in the field that can be used instead of natural gas for steam assisted gravity drainage (SAGD).
“It’s a one step process – we deal with all the principal heavy oil challenges in one simple step,” says Ed Veith, Ivanhoe Energy’s Executive Vice President, Upstream.
Upgrading heavy oil improves the hydrogen to carbon ratio of the product; that is, carbon is removed and/or hydrogen is added to the oil. There are different processes to achieve this, either removing carbon (carbon rejection) or adding hydrogen (hydro-cracking or hydro-treating). Traditional upgraders, such as cokers, use carbon rejection plus hydrogen addition.
HTL uses thermal cracking to break apart the long hydrocarbon chains, remove carbon and reassemble the chains with improved hydrogen-carbon ratios. Unlike traditional carbon rejection technologies, it’s able to do this very quickly, at scales as small as 10,000 barrels per day, and without the need for hydrogen, catalysts or significant pressure.
Furthermore, the process doesn’t create piles of environmentally challenging coke that is typically transported to distant markets.
The core HTL process consists of a re-heater vessel that heats sand, and a tall reactor tower where the reaction takes place.
The sand is circulated at high speed between the two.
The bitumen is injected into the bottom of the reactor tower where it meets a tornado of hot sand. The heavy oil molecules are thermally cracked into vapor form, and a thin film of coke is deposited on the sand grains.
The vapors are separated from the sand, drawn off and cooled into a lighter upgraded oil product, and the coke-covered sand is returned to the reheater where the coke is burned off, creating energy that is used to make steam.
The whole process takes place in a few seconds.
“On a total lifecycle basis, HTL provides net greenhouse gas savings as well as elimination of the volatile organic compounds and particulate emissions associated with coke handling and stockpiling,” says Veith.