Micro-action mechanism and macro-prediction analysis in the process of CO2 huff-n-puff in ultra-heavy oil reservoirs

Tian, Cong; Pang, Zhanxi; Dong, Liang; Wang, Xiaoyan; Hong, Qingjing; Chen, Jiajie; Zhang, Yang; Wang, Haifeng

doi:10.1016/j.petrol.2022.110171

Cited by 16 publications

(11 citation statements)

References 23 publications

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“…During CO 2 huff and puff, injection parameters such as injection pressure, soaking time, injection timing, and huff and puff cycles are important factors affecting shale oil recovery. − Through core experiments and nuclear magnetic resonance tests, Wan et al showed that after CO 2 injection, the light components in the crude oil would be replaced first and the heavy components in the crude oil would be gradually replaced with the increase of huff and puff cycles. In the early stage of CO 2 injection, the crude oil in macropores is mainly extracted, and the crude oil in micropores can be moved in the later stage of huff and puff .…”

Section: Introductionmentioning

confidence: 99%

Insights into Enhancing Shale Oil Recovery Postfracturing with CO₂ Huff and Puff and Elastic Depletion Development Strategies

Li,

Huang,

Duan

et al. 2024

Energy Fuels

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After hydraulic fracturing, shale reservoirs often undergo rapid production declines during depleted development, resulting in a low cumulative production. CO 2 huff and puff emerges as a promising method to enhance shale oil recovery postfracturing. This study conducted independent experiments to investigate multistage depressurization elastic depletion development and the CO 2 huff and puff method in shale oil. The effects of injection pressure, temperature, fractures, and other parameters on the CO 2 huff and puff recovery were analyzed using nuclear magnetic resonance (NMR). The impact of the CO 2 huff and puff on crude oil in different pores was elucidated. The results show that the fluid mobility of the shale reservoir is poor, with the recovery rate of elastic depletion development being less than 10%. Conversely, a CO 2 huff and puff can enhance the recovery rate by up to 20%. The recovery rate of shale oil through a CO 2 huff and puff correlates positively with injection pressure and temperature. The initial cycle of huff and puff contributes the most to crude oil recovery, reaching up to 50%. Under equivalent parameter conditions, the presence of fractures can increase the CO 2 huff and puff efficiency by 20% compared to the matrix core. Combined with NMR experiments, the lower limit of pores that oil can be produce in matrix and fracture cores in elastic depletion development is 200 and 150 nm, respectively. In the context of CO 2 huff and puff development, these values decrease to 30 nm for matrix cores and 15 nm for fractured cores.

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Section: Introductionmentioning

confidence: 99%

Insights into Enhancing Shale Oil Recovery Postfracturing with CO₂ Huff and Puff and Elastic Depletion Development Strategies

Li,

Huang,

Duan

et al. 2024

Energy Fuels

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“…In this context, some investigations on improving the performance of cyclic steam injection are carried out [14][15][16]. A novel means of mitigating steam channeling and premature steam breakthrough in steam flooding is to add a high-temperature gel [9,10,17,18].…”

Section: Introductionmentioning

confidence: 99%

Machine-Learning-Assisted Identification of Steam Channeling after Cyclic Steam Stimulation in Heavy-Oil Reservoirs

Liu

Jiao

et al. 2023

Geofluids

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Cyclic steam stimulation (CSS) is one efficient technology for enhancing heavy-oil recovery. However, after multiple cycles, steam channeling severely limits the thermal recovery because high-temperature steam preferentially breaks through to the producers. To solve the issues of steam breakthrough, it is essentially important and necessary to recognize steam channeling. In this work, a machine-learning-assisted identification model, based on a random-forest ensemble algorithm, is developed to predict the occurrence of steam channeling during steam huff-and-puff processes. The set of feature attributes is constructed based on the permeability ratio, steam quality, and steam-injection speed, which provides the reference for the construction of the training-sample set, steam-channeling reconstruction set, and prediction set. Based on the realistic data, the Pearson correlation coefficient is implemented to confirm the linear correlation among different characteristics; thus, the dimension reduction of the characteristic parameters is achieved. The random oversampling method is adopted to treat the unbalanced training-sample set. Our results show that this model can accurately describe the current state of steam channeling and predict steam propagation in the following cycles.

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“…In the supercritical state, CO 2 has the characteristics of low viscosity and strong diffusivity, which can enter small pores and promote oil production and thus improve the oil recovery. 20,21 CO 2 flooding can be divided into miscible flooding, nearmiscible flooding, immiscible flooding, and carbonized water flooding. 22−25 Compared with immiscible flooding, the nearmiscible and miscible flooding methods have a better displacement efficiency.…”

Section: Introductionmentioning

confidence: 99%

“…Gas injection production has become the main means of increasing oil production in tight reservoirs. − Especially, CO 2 flooding can not only greatly improve the oil recovery of low-permeability tight reservoirs but also realize the geological storage of CO 2 . − For example, Liu et al (2022) proposed dimethyl ether and propanol as efficient agents in assisting conventional CO 2 flooding for oil recovery while increasing CO 2 storage in reservoirs. , CO 2 -enhanced oil recovery mainly includes reducing viscosity of crude oil, swelling effect of crude oil, wettability alteration, and change of interfacial properties. − When the temperature is higher than 31.1 °C and pressure is higher than 7.38 MPa, CO 2 enters a supercritical state. In the supercritical state, CO 2 has the characteristics of low viscosity and strong diffusivity, which can enter small pores and promote oil production and thus improve the oil recovery. , …”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the CO₂ Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

Gao

Luo

Xie³

et al. 2022

Energy Fuels

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The microscopic pore structure of tight sandstone reservoirs significantly impacts CO2 flooding characteristics. In this work, two types of realistic sandstone visualization models were selected based on petrophysical properties and the pore structure feature. CO2 flooding experiments under different injection pressures and volumes were carried out using the in-house high-temperature and -pressure visualization flooding system. Then, the characteristics of oil movement and residual oil distribution were quantitatively described and analyzed for two rock types. The results show that the type I model has better physical properties and a more favorable pore structure, thus a higher oil recovery than the type II model. The immiscible CO2 flooding efficiency of the type I model is up to 64.5%. On the other hand, the oil recovery of the type II model increases when the miscible pressure is reached, and the maximum oil recovery is 49.5%. In the high-pressure miscible flooding stage, two types of models have similar oil recovery increments, which are 10.7 and 10.6%, respectively. Additionally, the residual oil distribution varies with the pore structure. The type I model has a small residual oil region and thus a high oil recovery efficiency. In contrast, the residual oil saturation of the type II model is larger, and the final oil recovery decreases. Furthermore, as the injection pressure and volume increase, the residual oil saturation becomes smaller, and oil recovery of both models increases. The occurrence characteristics of residual oil are oil droplet, cluster-shaped residual oil, flake oil, and dead corner oil, and the main influencing factors are capillary force, injection pressure, and pore connectivity.

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Micro-action mechanism and macro-prediction analysis in the process of CO2 huff-n-puff in ultra-heavy oil reservoirs

Cited by 16 publications

References 23 publications

Insights into Enhancing Shale Oil Recovery Postfracturing with CO₂ Huff and Puff and Elastic Depletion Development Strategies

Insights into Enhancing Shale Oil Recovery Postfracturing with CO₂ Huff and Puff and Elastic Depletion Development Strategies

Machine-Learning-Assisted Identification of Steam Channeling after Cyclic Steam Stimulation in Heavy-Oil Reservoirs

Experimental Investigation of the CO₂ Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

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Micro-action mechanism and macro-prediction analysis in the process of CO2 huff-n-puff in ultra-heavy oil reservoirs

Cited by 16 publications

References 23 publications

Insights into Enhancing Shale Oil Recovery Postfracturing with CO2 Huff and Puff and Elastic Depletion Development Strategies

Insights into Enhancing Shale Oil Recovery Postfracturing with CO2 Huff and Puff and Elastic Depletion Development Strategies

Machine-Learning-Assisted Identification of Steam Channeling after Cyclic Steam Stimulation in Heavy-Oil Reservoirs

Experimental Investigation of the CO2 Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus

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Product

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Insights into Enhancing Shale Oil Recovery Postfracturing with CO₂ Huff and Puff and Elastic Depletion Development Strategies

Insights into Enhancing Shale Oil Recovery Postfracturing with CO₂ Huff and Puff and Elastic Depletion Development Strategies

Experimental Investigation of the CO₂ Flooding Characteristics of Tight Sandstone Reservoirs Using a High-Temperature and -Pressure Visualization Apparatus