Getting Bitumen and Extra Heavy Oil to Market: Tight Oil Synergy, Blending, and Partial Upgrading Alternative Challenges Including Thermal Cracking Product Dienes, Gums, Self-Incompatible Asphaltenes, and Pricing
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Bitumen and extra heavy must be transported to markets. Various methods are used to move bitumen from formation to site tankage. From the well site, the produced bitumen can be shipped hot by rail without any blending. For non-heated transport, including rail and pipeline transportation, the extra heavy oil or bitumen must meet a significantly lower density or viscosity specification. To lower the viscosity various diluents are used and the blend is named by the diluent, e.g. dilbit, synbit, etc.. As an alternate, the dilbit is taken to an upgrader, the diluent removed, the virgin light end removed, and the vacuum bottoms upgraded by solvent deasphalting, hydrocracking, and/or thermal cracking, usually coking, followed by hydrotreating the virgin and cracked products, making a high gravity, low sulfur Synthetic Crude Oil, with acronym SCO, which sells at a premium, or is used for blending.
Some twenty in-situ down hole methods are in various stages of pilot and testing, and over forty field located partial upgrading schemes have been proposed to produce a lower viscosity material at the well-site, upstream, or midstream, that would require less diluent or natural gas. For example Fluid Catalytic Cracking, FCC, analogues UOP-CCU, Catalytic Crude Upgrading, Viscositor, IE-HTL, ETX-IYQ, NZ cracking use FCC configurations without hydrotreating the reaction product. For example, HTL uses high temperature short contact time to thermally crack vacuum bottoms.
All high temperature thermal cracked reactions yield unstable products and most are self-incompatible, which is completely different than stable and compatible SCO. Rather than overstate, confuse, or misrepresent the thermally degraded quality, partial upgraded material should be named differently, for example, Partially Upgraded Thermal Cracked Unstable Product would have acronym PUTCUP. PUTCUP with high olefins and dienes, disallowed by some pipelines, could be shipped like raw bitumen in rail cars, or if olefins allowed could be shipped like dilbit in pipelines or rail cars after blending with diluent to gravity or viscosity specification. PUTCUP includes heavy gum forming dienes in naphtha, jet and distillate fractions, self-incompatible asphaltenes and inorganic feed and produced solids in all fractions.
Patents and other open literature sources show short contact, high temperature reaction products, like FCC and high temperature short contact time products, like HTL distillates, are less stable than lower temperature longer contact time products like visbreaker and coker naphtha despite unsupported marketing claims otherwise. Simply, the higher the reaction temperature the more unstable product is formed, as shown by reaction product gases that have higher dienes including 1,3-butadiene. The higher the short contact reaction temperature the more 1,3-butadiene in product gas, and the more liquid dienes throughout the reactor product.
High temperature short contact time of fractions of seconds result in reactor and downstream plugging with gum formation and deposits caused by dienes in naphtha, jet and distillate fractions and self-incompatible asphaltenes precipitating and depositing with inorganic feed and produced solids. Thermal cracked product gum and asphaltenes deposit and plug reactors, transfer lines, quench towers, fractionation towers, downstream filters, catalyst guard beds, hydrotreaters, pumps, pipes and tanks. Self-incompatible PUTCUP is worse than just incompatible with other liquids as PUTCUP has precipitated, condensed and flocculated asphaltenes, semi-solids and solids that are out of solution, toluene insoluble, and cannot be resuspended or dissolved by any additive.
No partial upgraders have been built to prove reliable, long term operation of a year or more continuous operation, rather than a few hours of demonstration unit run. Proof of reliable operation with industry standard on-stream factors over 90-95% uptime is necessary to reduce high risk of a high capital cost investment in unproven processes. Partial upgraders typically don’t include hydrotreating to show a significantly lower capital cost compared to full upgraders, but without hydrotreating partial upgrading reactor product is problematic.
PUTCUP fractions are thermally degraded compared to crude or bitumen. PUTCUP price and refining value determination will be based on properties that are lower than coker product fractions, coker feed, and lower than par to crude oil like Brent or WTI. If there is a market for self-incompatible PUTCUP; self-compatible crudes have had their field production shut-in. Markets have indicated that the increase of lower cost frac oil will decrease light oil price, while demand for heavy oil to fill cokers will increase heavy oil price, resulting in a lower heavy-light differential and less incentive for partial upgrading, just as full upgrading projects have been abandoned. Reduced risk solutions to these partial upgrading challenges include the common practice of shipping bitumen in heated rail cars, or blending bitumen with diluent without partial upgrading.