Mechanistic simulation study of air injection assisted cyclic steam stimulation through horizontal wells for ultra heavy oil reservoirs

Wang, Yanyong; Ren, Shaoran; Zhang, Liang

doi:10.1016/j.petrol.2018.09.060

Cited by 41 publications

(10 citation statements)

References 30 publications

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“…they can be only safely and economically applied to the select few reservoirs having pay thicknesses of at least 15 m (Gates 2010;Zhao et al 2013Zhao et al , 2014. In addition to that, these technologies are not environmentally friendly as they emit substantial amount of carbon dioxide (CO 2 ) in the period of steam generation, have low efficiencies since they suffer from considerable wellbore heat losses, require considerable waste water handling and purification, and they do not provide appreciable oil upgrading within the reservoir (Gates and Larter 2014;Shi et al 2017;Wang et al 2019). Furthermore, in some of the field pilot cases, SAGD was shown to not be a net energy producer (Gates and Larter 2014).…”

Section: Introductionmentioning

confidence: 99%

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

Ado

2020

J Petrol Explor Prod Technol

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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).

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Section: Introductionmentioning

confidence: 99%

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

Ado

2020

J Petrol Explor Prod Technol

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“…However, some of the thermal enhanced oil recovery (EOR) processes, such as the steam-assisted gravity drainage (SAGD), the cyclic steam stimulation (CSS), and the steam flooding (SF), are not without disadvantages. Their disadvantages include: (i) suffering from considerable overburden, wellbore, and underburden heat losses, (ii) generating large amount of CO 2 during steam generation, (iii) achieving minor heavy-to-light oil upgrading, (iv) being applicable to only select few reservoirs, (v) generating large amount of wastewater, and (vi) having a low recovery factor compared to in-situ-combustion-type processes (Gates, 2010;Gates and Larter, 2014;Shi et al, 2017;Wang et al, 2019;Zhao et al, 2014Zhao et al, , 2013. The in-situ-combustion-type processes, such as conventional in situ combustion (ISC) and toe-toheel air injection (THAI), have been shown to have none of the disadvantages of the steam-based processes and have been shown to have so many advantages.…”

Section: Introductionmentioning

confidence: 99%

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

Ado

2021

J Petrol Explor Prod Technol

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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.

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“…At the same time, experts also show greater interest in the optimization of injection and production parameters of heavy oil steam flooding [30]. Some heavy oil recovery technologies with higher recovery efficiency have also been developed in combination with steam flooding [31][32][33].…”

Section: Introductionmentioning

confidence: 99%

The Impact of Plane Heterogeneity on Steam Flooding Development in Heavy Oil Reservoirs

Qu¹,

Ye²,

Ju³

et al. 2021

Lithosphere

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Steam flooding is proven to be an effective method to improve the development effect of heavy oil reservoirs. And steam flooding is the most common oil recovery technology for heavy oil reservoirs in China. However, because of the various reservoir physical properties, bring great challenges to successful steam flooding development. According to the previous research and development practice, we know that reservoir heterogeneity has a great influence on the development effect of water flooding. Due to the heterogeneity of reservoirs, the development of different injection-production well patterns will be affected. However, it is uncertain whether reservoir heterogeneity has an impact on steam flooding development effect. In order to clarify the above scientific issues, we take Xinjiang steam flooding oilfield as the research object to carry out relevant research. According to the reservoir distribution characteristics of Xinjiang Oilfield, three conceptual heterogeneity models representing permeability, thickness, and geometric plane heterogeneity are firstly proposed. Then, mathematic models with different plane heterogeneity of reservoir sand were built. Based on the mathematic model, initial conditions, boundary condition, and geological parameters of conceptual models, different steam flooding patterns were studied by applying numerical calculation. It is found that heterogeneity is an important geological factor affecting the development of steam flooding of heavy oil reservoir. And the results showed that cumulative oil production was different of different flood pattern at the same production condition. It can be concluded that the development effect of steam flooding of heavy reservoirs is strongly influenced by flood pattern. In order to improve development effectiveness of steam flooding of heavy oil reservoirs, flood pattern should be optimized. For each type of plane heterogeneity reservoir, a reasonable flood pattern was proposed. For plane heterogeneity of permeability, thickness, and geometry form, under the conditions of that as the producer was deployed in high permeability, thick, wide sand body and injector was deployed in low permeability, thin, narrow sand body, the recovery of steam flooding in heavy oil reservoir was better. Finally, how the three types of plane heterogeneity influence steam flooding of heavy reservoirs was discussed by adopting a sensitivity analysis method. The results show that the influence of permeability heterogeneity is the largest, thickness heterogeneity is the second, and geometric heterogeneity is the least. This conclusion can help us improve the development of this reservoir. And also, the findings of this study can help for better understanding of properly deployed well pattern and how to effective develop the heavy oil reservoirs of strong plane heterogeneity for other heavy oil reservoirs.

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Mechanistic simulation study of air injection assisted cyclic steam stimulation through horizontal wells for ultra heavy oil reservoirs

Cited by 41 publications

References 30 publications

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

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

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

The Impact of Plane Heterogeneity on Steam Flooding Development in Heavy Oil Reservoirs

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