Advanced assessment of in-situ thermal Enhanced Oil Recovery (EOR) to promote coproduction of both catalytically-upgraded oil and hydrogen gas

Claydon, Ryan (2021). Advanced assessment of in-situ thermal Enhanced Oil Recovery (EOR) to promote coproduction of both catalytically-upgraded oil and hydrogen gas. University of Birmingham. Ph.D.

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Abstract

As the complexity of light oil reservoirs requires greater expense in exploration and production, it is likely that more accessible heavy oil and bitumen reserves become increasingly attractive targets for development. The energy industry is manoeuvring towards greener energy sources. However, the ongoing transitional period will continue to demand a significant oil supply. Heavy oil and bitumen have high viscosity, high content of polyaromatics, and high heteroatom content including sulphur, nitrogen and heavy metals. Energy intensive refinery schemes are required to upgrade these oil types. In Situ Combustion (ISC) uses a small portion of the oil as a fuel source to refine oil in the subsurface, while leaving the deleterious upgrading products within the reservoir and generating hydrogen gas as a by-product. Heavy oil upgrading was studied using an inexpensive Layered-double hydroxide-derived Nienriched Mixed Metal Oxide (Ni-MMO), serving as an analogue to in situ reservoir minerals. The effects of upgrading were studied at 425ᵒC, under both pure H2 and N2 gas environments, 30 minute reaction time, a loading of 0.02g/g catalyst to oil ratio and an agitation of 500 rpm. The Ni-MMO catalyst generated superior liquid characteristics, decreasing the viscosity from 811 to 0.2 = mPa∙s, with the highest proportion of light naphthas under N2, increasing from 12.6% in the feed to 39.6% in the produced oil. The quantity of coke was saturated in sulphur indicating the generation of polyaromatic centres which served to remove the deleterious polyaromatic and asphaltic components from the oil.
A bespoke Mo-doped Ni-MMO was synthesised to improve the hydrogenation capability of the material. This was tested in the two-stage hydrogenation of naphthalene to tetralin and decalin. A comparison was made with typical first and second-stage hydrotreating catalysts including NiMo-Al2O3 and Pd1-5%-Al2O3. It was apparent that the Mo-doped Ni-MMO generated comparable hydrogenation activity to Pd2%-Al2O3, while the NiMo-Al2O3, catalyst was comparable to the Pd1%-Al2O3 catalyst. Reaction rate constants were derived in agreement with the rate-determining step demonstrated in previous works, with the exception of the Pd5%-Al2O3 catalyst which demonstrated the naphthalene conversion to tetralin as the rate determining step. It was made clear that the Ni and Mo bearing catalysts favoured the cis decalin isomer as the end hydrogenation product. This is important for subsequent ring-opening stages. The Pd-bearing catalysts favoured more significant conversion to trans-decalin. It was concluded that the electronic configuration of the catalyst was responsible for the disparity, influencing the orientation of the intermediate octalin species over the catalyst surface.

A conceptualisation of an offshore in situ combustion thermal EOR process in the North Sea was made for a partially-depleted and water-flooded reservoir. A pilot well pairing in a 500 ft x 500 ft reservoir package was modelled. Production data was predicted using the Marx & Langenheim steam heating model, with the coke deposition as the fuel used to generate steam. The production of oil was supplemented with hydrogen gas estimates relating to dehydrogenation of the in situ oil, and compared to experimental work which focused on tetralin dehydrogenation activity to represent heavier feedstocks. The most favourable condition for oil production generated peak production at approximately 1100 barrels/day. It was evident that the dehydrogenation reactions could contribute to a modest coproduction of hydrogen gas. Pd-Al2O3 catalysts showed the most promise in hydrogen generation at 250ᵒC peaking at 78 Barrel of Oil Equivalent (BOE) H2/day, while the Ni-MMO catalyst species generated enhanced dehydrogenation activity over a range of 250 to 300ᵒC compared to thermal dehydrogenation, reaching 35 boe H2/day.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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