Experimental study on liquid production law, oil recovery mechanism, and influencing factors of water huff-n-puff in the tight sedimentary tuff oil reservoir

Li, Shuai; Yang, Shenglai; Gao, Xinyuan; Wang, Mibang; Yu, Jing

doi:10.1016/j.petrol.2021.109721

Cited by 10 publications

(5 citation statements)

References 35 publications

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“…As production continues, the energy in the reservoir is gradually depleted. In summary, the oil production mechanism of water huff-n-puff includes imbibition, formation energy, and unsteady displacement. , Due to the existence of external force, the imbibition in the whole water huff-n-puff belongs to forced imbibition . The static imbibition in the soaking stage is the key to water injection huff and puff for oil recovery.…”

Section: Resultsmentioning

confidence: 99%

“…The pilot field tests was carried out in the structure of SL basin, which proved that the massive water huff-n-puff in tight oil reservoirs could achieve remarkable increase in productivity and economic benefits . Different from CO 2 -EOR by elastic expansion, reducing oil viscosity and mixing with oil, the oil recovery mechanism of water huff-n-puff includes imbibition and energy increase. , Li et al employed online nuclear magnetic resonance (NMR) to detect the changes in internal oil and water and confirmed the oil-increasing mechanism of supplementing formation elastic energy and high-pressure dynamic imbibition during the water huff-n-puff process . Based on the characteristics of tight reservoirs and oil recover mechanism of water huff-n-puff, it is found that water may affect oil recovery by gravity and capillary force during water huff-n-puff process. , Dynamic capillary force is the main reason for nonlinear flow in tight sandstone reservoirs .…”

Section: Introductionmentioning

confidence: 99%

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Oil Production Mechanism of Water Injection Huff-n-Puff for Enhancing Oil Recovery in Tight Sandstone Reservoir

Ji,

Yu,

Liu

et al. 2023

Energy Fuels

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It is difficult to establish an effective injection production well pattern in tight reservoirs, and water injection huff-n-puff is an important technology for EOR in late elastic energy development. The water injection huff-n-puff is established with a three-dimensional physical simulation experiment. The boundary conditions are simulated by setting up a pressure buffer device. The injection and production processes of horizontal wells are simulated by prefabricated artificial fractures at the injection port. The variation laws of 29 pressure points and 130 resistivity points can be effectively detected. Two cycles of experiments with different injection volumes are carried out, the change process of pressure and resistivity is analyzed, and the oil production mechanism is described. The fluid transfer velocity along the fracture extension direction is higher than that in the vertical fracture extension direction. The effect of the first cycle of the water injection huff-n-puff is significantly better than that of the second cycle. The change rule of oil recovery and oil change rate with different injection volumes shows that there is an optimal injection volume to maximize the on-site implementation benefits. The experimental results provide a theoretical and experimental basis for EOR by a water injection huff-n-puff in tight reservoirs.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Oil Production Mechanism of Water Injection Huff-n-Puff for Enhancing Oil Recovery in Tight Sandstone Reservoir

Ji,

Yu,

Liu

et al. 2023

Energy Fuels

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“…Imbibition characteristics of model no. 1 at different imbibition times: (a) saturated oil status, (b) imbibition 5 h, (c) imbibition 30 h, and (d) imbibition 288 h. Reprinted with permission from ref . Copyright 2022 Journal of Petroleum Science and Engineering.…”

Section: Results and Discussionmentioning

confidence: 99%

“…Comparison of model 2 before and after imbibition: (a) saturated oil status and (b) after 288 h of imbibition. Reprinted with permission from ref . Copyright 2022 Journal of Petroleum Science and Engineering.…”

Section: Results and Discussionmentioning

confidence: 99%

The Law and Mechanism of the Sample Size Effect of Imbibition Oil Recovery of Tight Sedimentary Tuff

Yang

Dong

et al. 2022

ACS Omega

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Imbibition is an important mechanism to improve the recovery factor (RF) of a tight oil reservoir. Accurately evaluating the oil production capacity of tight oil reservoirs by imbibition is of great significance for the formulation of oilfield production plans and productivity prediction. However, there is currently no unified regulation on the selection of rock sample size in tight oil reservoir imbibition evaluation experiments, resulting in great differences in reservoir imbibition oil production capacity obtained from rock samples of different sizes, which brings great challenges to the efficient development of tight oil reservoirs. To clarify the law and mechanism of the rock sample size effect of tight core imbibition oil recovery, this paper takes the newly discovered tight sedimentary tuff (TST) oil reservoir as an example. First, several representative real cores were collected. Then, their wettability and pore structure characteristics were analyzed. Finally, physical simulation experiments of imbibition under different rock sample sizes were conducted. The results show that the TST has very favorable imbibition conditions, which are manifested in the following: (i) the wettability is weakly hydrophilic to hydrophilic; (ii) the mineral composition is tuffaceous minerals, calcite, and quartz, without clay minerals; (iii) micro-nanoscale pores are developed; and (iv) the pore throats are evenly distributed. In the imbibition experiments of rock samples of different sizes, the oil production characteristics of the core surface, the variation form of imbibition rate, pore production characteristics, and the influence mode of imbibition pressure on imbibition do not have the sample size effect. However, the RF of the spontaneous imbibition has an obvious sample size effect, and there is a good exponential function relationship between the imbibition RF and the specific surface area (SSA) of cores. The fundamental reason why the rock sample size effect of the TST imbibition oil recovery is relatively stable and has strong regularity is that its pore structure and wettability are relatively homogeneous and stable. The change of rock sample size does not have a great impact on the distribution of the core pore structure and wettability, resulting in no significant change in its imbibition power, resistance, and distance. Therefore, the main factor determining the imbibition RF of rock samples with different sizes is their SSA. The research results of this work can provide an important theoretical basis for understanding the law and mechanism of TST imbibition oil recovery and unifying the imbibition experimental results of small-sized rock samples.

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“…With the help of nuclear magnetic resonance method, Li et al (2022) quantitatively investigated microscopic oil production characteristics after implementing huff-n-puff. It was discovered that intermediate pores contributed the most to oil production, which accounted for 74.02% [19]. performed numerical simulation to announce the impacts of the parameters of hydraulic fracturing on water huff-n-puff for tight oil exploitation [20].…”

Section: Introductionmentioning

confidence: 99%

Study on Oil Composition Variation and Its Influencing Factors during CO2 Huff-n-Puff in Tight Oil Reservoirs

et al. 2023

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With immense potential to enhance oil recovery, CO2 has been extensively used in the exploitation of unconventional tight oil reservoirs. Significant variations are observed to occur in the oil’s composition as well as in its physical properties after interacting with CO2. To explore the impacts of oil properties on CO2 extraction efficiency, two different types of crude oil (light oil and heavy oil) are used in CO2 huff-n-puff experiments. Moreover, numerical simulation is implemented to quantitatively inspect the impacts of different influencing factors including production time, reservoir pressure and reservoir temperature on physical properties as well as on the oil composition variation of the crude oil. The findings of the experiments demonstrate that, whether for the light oil sample or for the heavy oil sample, hydrocarbon distribution becomes lighter after interacting with CO2 compared with the original state. In addition, it is also discovered that the hydrocarbon distribution variation is more significant for the light oil sample. The findings of the numerical simulation suggest that production time, reservoir pressure and reservoir temperature have significant impacts on the produced oil composition and properties. The hydrocarbon distribution of the oil becomes lighter with the increasing of production time and formation pressure, while it becomes heavier with the increasing of reservoir temperature. At the very beginning of the oil production, the properties of the produced oil are worsened. Compared with the original state, the oil density and viscosity are 25.7% and 200% higher, respectively. It is suggested that viscosity reducers are added into the well to improve the oil properties in this period. With the continuing of the oil production, the oil properties are continuously promoted. At the end of the simulation time, the oil density and viscosity are 3.5% and 15.1% lower compared with the original oil, respectively. This paper has great significance for the implementation of CO2 huff-n-puff in tight oil reservoirs.

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Experimental study on liquid production law, oil recovery mechanism, and influencing factors of water huff-n-puff in the tight sedimentary tuff oil reservoir

Cited by 10 publications

References 35 publications

Oil Production Mechanism of Water Injection Huff-n-Puff for Enhancing Oil Recovery in Tight Sandstone Reservoir

Oil Production Mechanism of Water Injection Huff-n-Puff for Enhancing Oil Recovery in Tight Sandstone Reservoir

The Law and Mechanism of the Sample Size Effect of Imbibition Oil Recovery of Tight Sedimentary Tuff

Study on Oil Composition Variation and Its Influencing Factors during CO2 Huff-n-Puff in Tight Oil Reservoirs

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