Development of an in-situ oil conversion process to generate clean hydrogen

Lopeman, Thomas James (2024). Development of an in-situ oil conversion process to generate clean hydrogen. University of Birmingham. Ph.D.

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Abstract

There are huge reserves of heavy oil throughout the world that can be energy intensive to recover. Improving the energy efficiency of the recovery process and developing novel methods of cleaner recovery will be essential for the transition from traditional fossil fuel usage to net-zero. In-situ combustion (ISC) is a less used technique, with Toe-to-Heel Air Injection (THAI) and CAtalytic PRocessing In-Situ (CAPRI) being specialised novel versions of traditional ISC. They utilise a horizontal producing well and in the case of CAPRI, a catalyst. This project aims to investigate the impact that injected steam has on both the THAI and CAPRI processes for the purpose of in-situ heavy oil upgrading and will help to bridge the gap between the extant laboratory research and the unknown commercial potential. This thesis also presents a novel method for modelling the THAI-CAPRI method using CMG STARS, proposing an in-situ hydrogen production reaction scheme. THAI and CAPRI experimental-scale models were run under three conditions: dry, pre-steam and constant steam. Starting from a reservoir API (a measure of a hydrocarbon liquid’s density compared to water) of 10.5°, THAI reached an average API of ~16 points, observing no increase in API output with the use of steam injection. A decreased API output by ~0.7 points during constant steam injection was achieved due to a high temperature oxidation (HTO) dominant environment. This decreases reactant availability for thermal cracking. CAPRI dry run reached an API of 20.40 points and achieved increased API output for both pre-steaming (~21.17 points) and constant steaming (~22.13 points). The mechanics for this increased upgrading were discussed, and catalytic upgrading, as opposed to thermal cracking was shown to be the reason for the increased upgrading. Both processes produce similar cumulative oil (~3150 cm3) during dry and pre-steamed runs, only increasing to ~3300 cm3 with the constant steam injection during THAI and 3500 cm3 for CAPRI.
This thesis also investigates the possibility and extent of hydrogen generation during Toe-to-Heel Air Injection (THAI) applied to heavy oil via reservoir simulation. This was achieved by incorporation of hydrogen reactions such as coke gasification, forward and reverse water gas shift into the THAI model for ISC processes in heavy oil reservoirs. This enabled the interaction between components and reactions to be assessed. The reservoir simulation model was history matched using field data from the Kerrobert THAI field pilot; it successfully incorporated hydrogen reactions, showing good agreement. The inclusion of coke gasification reactions resulted in hydrogen production but reduced oil rates due to temperature decrease and increased gas saturation. Forward water-gas shift (FWGS) had negligible impact on oil production, due to reduced competition with cracking and oxidation reactions. Combined coke gasification and FWGS increased hydrogen production and slightly reduced oil rates. Reverse water-gas shift (RWGS) had minimal impact on hydrogen fraction. This thesis emphasises the importance of hydrogen reactions in the THAI model and their influence on the THAI process. It provides valuable insights for optimising THAI projects and underscores the role of reaction scheme choice in history matching.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):