Mechanisms and capacity of high-pressure soaking after hydraulic fracturing in tight/shale oil reservoirs

Wang, Jing; Liu, Huiqing; Qian, Genbao; Peng, Yongcan

doi:10.1007/s12182-020-00524-z

Cited by 20 publications

(6 citation statements)

References 34 publications

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“…frontiersin.org include injection rate, injection volume and soaking time (Wang et al, 2021), and the effect of these engineering parameters on the development effect was studied for the sixth round of water injection huff and puff.…”

Section: Frontiers In Energy Researchmentioning

confidence: 99%

Study on the development options of tight sandstone oil reservoirs and their influencing factors

Huang

et al. 2022

Front. Energy Res.

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The research area of tight sandstone oil reservoirs was selected, a numerical model of the oil reservoir was developed, and a study of the development options and influencing factors was carried out to analyze the influence of different development methods, physical and engineering parameters on the development dynamics. Study shows that the two main factors limiting the efficient development of tight sandstone reservoirs are reservoir properties and formation energy. Fractured horizontal well injection huff and puff development can effectively improve reservoir physical properties and timely replenish formation energy, which is suitable for the development of such oil reservoirs. In dense sandstone reservoirs, its impact on production capacity is also relatively small when the permeability ratio is small. Due to both gravity and reservoir physical properties, the permeability ratio increases, the cumulative oil production of positive rhythm reservoirs decreases and that of reverse rhythm reservoirs increases, and the location of high-quality reservoirs in the upper part of producing wells is conducive to increasing the final recovery rate. A lower oil to water viscosity ratio can significantly increase the swept volume and improve development effect. Hydrophilic reservoirs can reduce the injection pressure and increase the spread range, effectively improving the problem of inability to inject, and improving reservoir hydrophilicity through surface activators can increase reservoir recovery. The water injection rate determines the recovery rate of formation energy. Generally, the faster the rate, the higher the cumulative oil production. Therefore, the rate of water injection should be increased as much as possible, taking into account construction conditions and economic evaluation. Additionally, the effect of water injection on the development effect is different at different stages, so the appropriate timing of water injection is very important to the water injection huff and puff development effect, and the use of early water injection in this research area is not conducive. Soaking can promote pressure and fluid redistribution and improve water injection huff and puff development effect, but soaking for a long time can lead to reservoir contamination and reduce crude oil production, so the preferred time for a soaking is about 20 days.

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Section: Frontiers In Energy Researchmentioning

confidence: 99%

Study on the development options of tight sandstone oil reservoirs and their influencing factors

Huang

et al. 2022

Front. Energy Res.

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“…As one of the critical resources, tight oil has attracted much attention in recent years owing to its extensive distribution. − However, the widespread presence of nanopore throats results in extremely low permeability in tight reservoirs, severely limiting tight oil mobility. The effects of complex reservoir heterogeneity conditions on tight oil mobility are not fully understood, which include tight oil composition, rock and mineral types, pore radius distribution, etc.…”

Section: Introductionmentioning

confidence: 99%

Layered Threshold Pressure of Tight Oil in Nanopores: A Molecular Dynamics Simulation Study

Wang

Zhang

et al. 2023

Energy Fuels

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Nanoscale pores are widely developed in tight oil, and the scale effect significantly affects the dynamic behavior of crude oil molecules at different positions in the nanopores. The molecular dynamics simulation method was used to study the mechanism of threshold pressure of tight oil molecules at different positions in quartz and calcite nanopores and the influence of pore radius on threshold pressure. The results show that the mobilizing of crude oil molecules at different positions in nanopores is mainly affected by liquid−solid interactions and intermolecular friction. The interactions between naphthenic acids and pore walls are the main contributing factor to the threshold pressure of boundary crude oil molecules. Van der Waals interaction and weak hydrogen bonds mainly contribute to the bonding of naphthenic acids with quartz walls, and strong electrostatic interaction and strong hydrogen mainly contribute to that with calcite walls. Except for the boundary layer, the threshold pressure of other layers relates to the interactions between saturated hydrocarbon, aromatic hydrocarbon, and adjacent layers as well as the molecular friction, among which friction between the saturated hydrocarbon and the adjacent molecules is dominant. It is challenging for crude oil to mobilize in quartz pores smaller than 3 nm. However, when the quartz pore width exceeds 7 nm, the mobilizing law of crude oil is scarcely affected by the pore width. The mobilizing laws of crude oil differ in calcite pores smaller than 11 nm, while that stays nearly the same in pores larger than 11 nm. Finally, a prediction model for the threshold pressure of tight oil molecules at different positions in quartz and calcite nanopores is proposed, which provides theoretical guidance for precise control of working fluid properties to improve tight oil recovery.

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“…During the fracturing, a large amount of fracturing fluids are injected into the formation, and the flow-back rate is usually low [5]. A large amount of fracturing fluids is retained in the formation, and previous researches on fracturing fluid retention in the formation have been conducted.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Distribution of Retained Fracturing Fluids and Its Effect on the Permeability and Wettability in Tight Oil Reservoirs

Tuo

Fan

et al. 2023

Geofluids

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It is not clear how the distribution of retained fracturing fluids and its effect on the permeability and wettability in tight oil reservoirs interact. Especially, there are more qualitative studies and less quantitative studies on this issue. Under laboratory experimental conditions, this paper clarifies the distribution of retained fracturing fluids in the core and reveals the influence rule of retained fracturing fluids on tight reservoir permeability and wettability. It is found that the main retention space of retained fracturing fluids in a tight reservoir is a microporous interval, and the residual oil after oil displacement by retained fracturing fluids mainly exists in the core in the form of dots or porphyries. The smaller permeability and porosity of the core will lead to more retained fracturing fluids. The permeability of different cores after fracturing fluid retention has decreased to varying degrees compared with that before fracturing fluid retention. The wettability of core slices before and after fracturing fluid retention was tested, and the effect of retained fracturing fluids on reservoir wettability was not significant. This study has important significance for improving the recovery of tight oil reservoirs and enhancing the understanding of postfracturing fluid retention.

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Mechanisms and capacity of high-pressure soaking after hydraulic fracturing in tight/shale oil reservoirs

Cited by 20 publications

References 34 publications

Study on the development options of tight sandstone oil reservoirs and their influencing factors

Study on the development options of tight sandstone oil reservoirs and their influencing factors

Layered Threshold Pressure of Tight Oil in Nanopores: A Molecular Dynamics Simulation Study

Experimental Study on the Distribution of Retained Fracturing Fluids and Its Effect on the Permeability and Wettability in Tight Oil Reservoirs

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