A detailed approach to up-scaling of the Toe-to-Heel Air Injection (THAI) In-Situ Combustion enhanced heavy oil recovery process

2021

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As governments around the world prepare for a transition period to a decarbonised energy and economic future, petroleum is needed to smoothen that transition. Based on the analysis of the International Energy Agency’s 2020 projections, around 770 billion barrels of oil are required to meet demand from now to 2040. However, according to British Petroleum’s Statistical Review of World Energy 2020, as at the end of 2019, the global total reserves of recoverable conventional and unconventional oils is approximately 1734 billion barrels. Out of that, the conventional easy-to-produce light oil accounts for only 30% (i.e. accounts for only 520.2 billion barrels). Therefore, the remaining 249.8 billion barrels of oil needed to satisfy demand up to 2040 must come from unconventional oils, namely heavy oils and bitumen. However, these unconventional resources are very difficult to produce and the current production methods have very high environmental footprints. Consequently, in accordance with climate crisis mitigations, the vast reserves of the virtually unexploited heavy oils and bitumen must be developed using advanced and greener extraction technologies, such as the yet-to-be-fully-understood THAI process which provides partial upgrading of heavy oil/bitumen via in situ combustion. Using validated numerical models which are developed using the CMG’s reservoir thermal simulator, the STARS, which is also used in this study, field scale reservoir simulations of the THAI process were performed with the wells arranged in staggered line drive (SLD) and direct line drive (DLD). Over the 834 days of operating time, the cumulative oil recovery in SLD is 32% of oil originally in place (OOIP) which is equivalent to 26,100 m3 whilst that in DLD is 27% OOIP. This shows that more oil (i.e. an additional 5% OOIP) was cumulatively recovered in SLD compared to in DLD model. It is found that smaller reservoir volume was swept by the combustion front in DLD and thus making the heat-affected reservoir volume smaller than that in SLD model. Furthermore, in DLD, due to the nearness of the injector well to the toe of the horizontal producer (HP) well, oxygen production began much earlier, compared to in the SLD. It is also found that the temperature of the mobile oil zone is higher in the SLD model compared to that in the DLD model. This implies that higher quality oil is produced when the wells are configured in the SLD pattern. Therefore, this first-of-a-kind work has shown that SLD arrangement is far more efficient, safer, and produces higher quality oil than DLD pattern and that actual process engineering designs should use SLD wells configuration.

Section: Athabasca Bitumen Kinetics Scheme and Its Parameterssupporting

confidence: 90%

Section: Pvt Properties Of Athabasca Bitumenmentioning

confidence: 99%

Section: Athabasca Bitumen Kinetics Scheme and Its Parametersmentioning

confidence: 99%

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Improving heavy oil production rates in THAI process using wells configured in a staggered line drive (SLD) instead of in a direct line drive (DLD) configuration: detailed simulation investigations

2021

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“…The main advantages of the THAI process, in situ combustion, and the conditions for process stability are summarized elsewhere (Turta and Singhal 2004;Xia et al 2005;Greaves et al 2008;Gutierrez et al 2009;Liang et al 2012;Rabiu Ado et al 2017;Rahnema et al 2017;Rabiu Ado et al 2018;Zhao et al 2018;Chen et al 2019;Zhao et al 2019). Furthermore, the THAI process has been the subject of detailed numerical simulations both at laboratory scale and at field scale (Rabiu Ado et al 2017, 2018Ado et al 2019;Ado 2019Ado , 2020a.…”

Section: Introductionmentioning

confidence: 99%

Effect of reservoir pay thickness on the performance of the THAI heavy oil and bitumen upgrading and production process

2020

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The increasing energy demand has to be met while we transitioned to a decarbonized energy future. Heavy oil and bitumen reserves are urgently needed to be developed to ensure that a smooth transition is provided. In this work, field-scale kinetics parameters are used to study the effect of reservoir pay thickness on the performance of toe-to-heel air injection (THAI) process. Air was injected at constant rate into three different models with the thicknesses of 24 m, 16 m, and 8 m, respectively. The oil produced is slightly affected by the reservoir thickness. It is found that the lower the reservoir thickness, the larger the cumulative air-to-oil ratio (cAOR), indicating that heat loss increases with the decrease in the reservoir thickness. This trend is similar to steam-based processes. At constant air injection flux, it is found that both the cumulative oil produced and the cAOR decrease with the decrease in the reservoir thicknesses. This decrease is attributed to the decrease in the rate of heat generation in the thinner reservoirs, which in turn results in lower combustion zone temperature and thus lower temperature gradients between the reservoir and the overburden and the reservoir and the underburden. Consequently, a more general conclusion is that decreasing the air injection rate by the same factor the reservoir thickness is decreased (i.e. keeping the air injection flux constant) results in a more economical THAI process operation compared to when the air injection rate is kept constant (i.e. allowing increase in air injection flux).

“…The THAI process on the other hand falls into the category of the so-called "short-distance displacement" processes (Turta and Singhal, 2004 ), and laboratory studies have shown it to exhibit very high recovery factors of up to 85% of oil originally in place (OOIP) and to provide upgrading by up to 8.2° API (Greaves et al, 2008 , 1999 ; Xia and Greaves, 2006 ). The THAI process has been extensively studied at laboratory (Greaves et al, 2008 ; Turta and Singhal, 2004 ; Xia et al, 2002a , 2002b , 2002c ; Xia and Greaves, 2006 , 2002 ; Xia et al, 2002a ; Zhao et al, 2021 , 2018 ), via laboratory-scale and field-scale numerical simulations (Ado, 2021 , 2020a , 2020b , 2020c ; Ado et al, 2019 ; Greaves et al, 2012a , 2012b , 2012c ; Rabiu Ado et al, 2018 , 2017 ) and at pilot and semi-commercial scales (Petrobank, 2009 , 2008 ; Touchstone, 2016 , 2015 ; Turta et al, 2020 ; Wei et al, 2020a , 2020b ). These studies have shown that when compared against other heavy oils recovery techniques, the THAI process has the following realizable potentials: (i) energy-self-sufficiency when waste heat is used to run utilities, (ii) having minimal surface-footprint as no surface upgrading facilities are needed, (iii) potential for being carbon-capture-ready so that the captured CO 2 can be sequestered or be used for EOR, etc.…”

Section: Introductionmentioning

confidence: 99%

Detailed investigations of the influence of catalyst packing porosity on the performance of THAI-CAPRI process for in situ catalytic upgrading of heavy oil and bitumen

2021

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Heavy oils and bitumen are indispensable resources for a turbulent-free transition to a decarbonized global energy and economic system. This is because according to the analysis of the International Energy Agency’s 2020 estimates, the world requires up to 770 billion barrels of oil from now to year 2040. However, BP’s 2020 statistical review of world energy has shown that the global total reserves of the cheap-to-produce conventional oil are roughly only 520.2 billion barrels. This implies that the huge reserves of the practically unexploited difficult-and-costly-to-upgrade-and-produce heavy oils and bitumen must be immediately developed using advanced upgrading and extraction technologies which have greener credentials. Furthermore, in accordance with climate change mitigation strategies and to efficiently develop the heavy oils and bitumen resources, producers would like to maximize their upgrading within the reservoirs by using energy-efficient and environmentally friendly technologies such as the yet-to-be-fully-understood THAI-CAPRI process. The THAI-CAPRI process uses in situ combustion and in situ catalytic reactions to produce high-quality oil from heavy oils and bitumen reservoirs. However, prolonging catalyst life and effectiveness and maximizing catalytic reactions are a major challenge in the THAI-CAPRI process. Therefore, in this work, the first ever-detailed investigations of the effects of alumina-supported cobalt oxide–molybdenum oxide (CoMo/γ-Al2O3) catalyst packing porosity on the performance of the THAI-CAPRI process are performed through numerical simulations using CMG STARS. The key findings in this study include: the larger the catalyst packing porosity, the higher the accessible surface area for the mobilized oil to reach the inner coke-uncoated catalysts and thus the higher the API gravity and quality of the produced oil, which clearly indicated that sulphur and nitrogen heteroatoms were catalytically removed and replaced with hydrogen. Over the 290 min of combustion period, slightly more oil (i.e. an additional 0.43% oil originally in place (OOIP)) is recovered in the model which has the higher catalyst packing porosity. In other words, there is a cumulative oil production of 2330 cm3 when the catalyst packing porosity is 56% versus a cumulative oil production of 2300 cm3 in the model whose catalyst packing porosity is 45%. The larger the catalyst packing porosity, the lower the mass and thus cost of the catalyst required per m3 of annular space around the horizontal producer well. The peak temperature and the very small amount of produced oxygen are only marginally affected by the catalyst packing porosity, thereby implying that the extents of the combustion and thermal cracking reactions are respectively the same in both models. Thus, the higher upgrading achieved in the model whose catalyst packing porosity is 56% is purely due to the fact that the extent of the catalytic reactions in the model is larger than those in the model whose catalyst packing porosity is 45%.