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. 2025 May 21;15(1):17637.
doi: 10.1038/s41598-025-02520-y.

Development and performance evaluation of multi-functional slickwater fracturing fluid system for shale reservoirs

Qi Li  1   2 , Xiaoyan Wang  3   4 , Dongping Li  3 , Yiyang Tang  5 , Hongjiang Ge  3   4
Affiliations

Development and performance evaluation of multi-functional slickwater fracturing fluid system for shale reservoirs

Qi Li et al. Sci Rep. .

Abstract

The rapid decline in energy and production following the primary fracturing development of shale oil reservoirs, and the low production of single wells are the problems facing the development of Cangdong shale oil in the Bohai Bay Basin. A multi-functional fracturing fluid system with emulsification, viscosity reduction, oil washing, and wettability improvement was developed by introducing a mixed-charge surfactant (PSG) to environmentally friendly and low-cost slickwater fracturing fluid (SWFF). The evaluation focused on several key properties including temperature and shear resistance, interfacial activity, viscosity reduction, wettability, and oil washing, all of which were assessed through laboratory experiments. The results showed that the 0.2% PSG and SWFF have high compatibility, forming a functional fracturing fluid system that exhibits exceptional temperature and shear resistance, as well as high interfacial activity. The rate of emulsification and viscosity reduction between the system and GY734H shale oil exceeds 93.45%. Moreover, the system is completely demulsified after being left to stand at 70 °C for 2 h. Furthermore, the static oil washing efficiency of the functional fracturing fluid system at 80 °C is 20.99%, while the SWFF is only 11.65%, which confirms the indoor effectiveness of the system. With the further optimization and application of the multifunctional slickwater fracturing fluid system (SWFF + PSG), it is expected to play an important role in the efficient development of shale reservoirs in the Bohai Bay Basin.

Keywords: Cangdong Sag; Fracturing fluid; Oil washing; Shale oil; Viscosity reduction.

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Conflict of interest statement

Declarations. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Molecular structure of PSG surfactant.
Fig. 2
Fig. 2
Temperature and shear resistance of SWFF and SWFF + PSG systems.
Fig. 3
Fig. 3
The IFT between the fracturing fluid system and GY734H shale oil.
Fig. 4
Fig. 4
Images of the emulsifying and viscosity reduction process of shale oil by using fracturing fluid at 70 °C: (a) at the beginning and un-emulsified, (b) after emulsifying for 0 h, and (c) after standing for 2 h.
Fig. 5
Fig. 5
Viscosity and viscosity reduction rate of shale oil after emulsifying and viscosity reduction.
Fig. 6
Fig. 6
Microscopic images of shale oil after emulsifying and viscosity reduction: (a) SWFF, (b) SWFF + 0.2%PSG, (c) SWFF + 0.4%PSG, and (d) SWFF + 0.6%PSG.
Fig. 7
Fig. 7
Mechanism diagram of W/O transforming into O/W emulsion.
Fig. 8
Fig. 8
Relationship between demulsification rate of shale oil emulsions after viscosity reduction and time at 70 °C.
Fig. 9
Fig. 9
Effect of fracturing fluid system on contact angle between shale and water: Shale core immersed in (a) field water, (b) GY734H shale oil, (c) SWFF, (d) SWFF + 0.2%PSG, (e) SWFF + 0.4%PSG, and (f) SWFF + 0.6%PSG for 24 h, respectively.
Fig. 10
Fig. 10
Static oil washing efficiency of fracturing fluid system on GY734H oil sand at 80 °C.
Fig. 11
Fig. 11
Proposed mechanism of multifunctional fracturing fluid to enhance shale oil recovery.
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